Rotary hammer.



H. M. PLAISTED.

nonnv HAMMER.

APPLICATION FILED `IlINE 3.1918.

1,281,829. Pat/@umd 0111.151918.

UNITED STATES PATENT lOFFICE.

HAROLD M. PLAISTED, OF GRANITE CITY, ILLINOIS, ASBIGNOB T0 WILLIAMS PATENT CBUSHER AND PULVEBIZEB. C0., OF MISSOURI.

sr. Louis, mssounr, a conromrrron or ROTARY HAMMER.

Spe'oication of Lettersatent.

Patented Oct. 15, 1918.

Application Jed June 3, 1918. Ser1alNo.237,907.

y To all whom t may concern:

A disks C-fCl-Cz--C etc., that carry hamy longitudinal .central line Be it known that I, HARoLD M. PLAISTED, a citizen of the United States, and residing at Granite Cit in the county of Madison and State of I linois, have invented certain new and useful lImprovements in Rotary Hamme-rs, of which the following is a 'specifcation.

This .invention relates to certain new and useful improvements in rotary hammers for grinders, pulverizers, and like reducin machines, the peculiarities of which wil be hereinafter described and claimed.

The main object of my invention is the provision of a rotary hammer of such pivotal mounting and arrangement of adjacent, parts, that the operative edges will have effective cage clearance, and will clear adjacent hammers.

In the accompanying drawing on which like reference letters indicate corresponding parts, Figure l represents a artial sectional elevation of any suitable re ucing machine, embodying my invention; Fig. 2, a horizontal sectional view on the line X of Fig. 1,

looking upward; Fig. a detail view of my hammer; and Fig. 4 another form of .my hammer.

The general style of grinders to which my improvements are especially applicable, is shown in Patent No. 1,266,894, dated May 21, 1918, to which reference is made for illustration of detail construction not shown herewith.

The letter A designates an arcuate cage, concentric with a shaft B on which are keyed lner rods D on which are pivoted hammers thatcoperate with said cage in grinding the material supplied thereto. These ham-A mers each consist preferably of. flat bar steel of`suitable thickness, the parallel sides E of which constitute a shank. At the outer end of said shank are located operative or cutting edges F--F extending across the thickness of the barand equally distant from aA G and preferably formed atfthe extremities oi lateral angular projections formed by the outwardly diverging sides and a. square or other shaped outer 4end I. These symmetrical yopleratlve edges may be votherwiseformed. T e oppositeorI inner end of saidshank is shown 4in Figs. 1 and. 3, as being widened to sides E' that meet a square inner end K at right angles as shown, and join the sides E by an arc about the center L of a hole that is located substantially an equal distance from the inner end K and from the nearer side E', but is also eccentric to, or at one side of the central line` G. This hole is for pivotally mountin the hammer on the respective rod D, an the operative edge F on the opposite side of the line G is farther from the center` L than is the edge F that is on the same side of the axis as the center L. lVhen the hammer is mounted on its rod D, and the shaft is rotated in the direction of the arrow, the center of gravity of the hammer will be normally located on a radial line from the shaft B and the hammer will assume substantially the position shown at R and R1. In this'normal position of rotation, the forward edge F is 1n front of the radial-line through the center of gravity of the hammer. Under the resistance of the materialbeingr ground the forward edge will a proach closest to. thc cage when it falls bac t to this line, as shown at R2. The rear edgeF however, on account of being nearer to the center L, anden the opposite side, of the line G, will be approximately four times farther from the cage thanF, in the posit-ion of the hammer shown at R and'R1; and this noportion increases to approximately ten times when the hammer is in Athe position shown at R2.

This comparative location of-the front and rear edges brings the forward edge in its cooperative positlon, close to the cage,\while it withdraws the rear edge more and more from the' material being ground and away from the cage,thus avoiding dullng the rear edge, and also providing clearance for the forward ed e.

At R1 is indicated at M and N, the usual and maximum Wear respectively, before reversing the hammers on the` hammer rods so as to bring theedge F to the front as the working edge. This is done by means of a corresponding hole, the center L of which (see Fig. 3)l is located on the Voppositeside ofthe line G, diagonally from the center' of the hole L, and bears a reverse relation .to

center-L; that is, the edge F' is a farther distance from L than is the edge E: the

distance between F and L is substantially the same as between F andL, andthe distance F L is substantially the same as FIL'.

In other words the herinner' pivot holes, the.

cutting or operative edges, and the side edges of the shank, are all symmetrically located with regard to the central longitudiing .edge 2j-1;*- at R?, the vhammer has I recede'd slightly, nder teStance of the' materlal;

4 contact With-.said

nal line G through the shank. edge F is Worn back as mentioned above, and the hammer is reversed so as to pivot on the center L the edge F Will approximate the position indicated at R2 and will practically renew the effective or cutting action of the hammers for a further period.

Fig. 4 shows another form of my hammer, in which the hub Width E-E of Fig. 3 is continued the length of the shank. This avoids forge Work at the inner end. Near the outer end are provided corresponding holes,- the centers L2 and L3 of which bear the same relation to the inner corner edges F2 and Fa respectively, as L and L 'bear to lthe other operative edges F and F. VVl1en the outer edges F and F are successively Worn down as indicated at M, the hammer can be remounted successively to pivot on the centers L2 and L3; the corner edges F2 and F3 Will thus become successively the operative edge, and further efective use of said hammer is provided.

The operative,A edges F-F are shown in Figs. 3 and 4 as projecting laterally beyond the side edges EE of the shank, and ar equi-distant from the axis G.

The length of the operative or cutting edge maybe the Width of the hammer, or may bemore or less, according to the shape best lsuited to reduce the material fed to t e hammers.

In order to prevent dulling the corners of the operative edges by contact with adjacent preferably by means of a bearing edge 2v and a bearing edge 3 formed by cut-out portions of each disk plate at alternate hammer rods, thus forming a pocket 1n connection with a clearance arc 4. When the hammer is in the position. shown by full lines at R and R-, thesideedg'e'of the hub Width Ev is substantially incontactwith the'v bearthe. dot-te, positiefl at ,R1 indicatesthe` @side edge" f't When the.

ie: hammer being limited-in its.

more,.to correspond to the hub Width of said shank. Being .on the same side of the harnmer, the stop edges are ,more accurately located with respect to the actual pivot center or hammer rod.

I claim:

1. A rotary hammer comprising a fiat bar shank provided with an operative edge at one end on each side of the central line of the shank, and having pivot holes located on opposite sides of said line near the other end.

2. A rotary hammer comprising a flat bar shank provided With outwardly diverging lateral projections at one endl of said shank, having a pair of holes near the other end adapted for pivotal mounting.

3. A rotary hammer comprising a fiat bar shank provided at each end on opposite sides thereof with operative edges substantially equi-distant from the central line of the shank, and also with a pair of holes nearv other pair of operative edges separated laterally a farther distance than the first pair, said shank having a pair'of holes near each end thereof, equi-distant from said axis for pivotal mounting, yand each hole being equidistant from the farthest operative edge respectively.

5. The combination with a shaft, a suitable casing oscillatable rotary pivoted harnmers having sharp edges at front and rear faces and having contact portions on one face of the shank near the ivot end, of a set of disks substantially as t ick as the hammers having pockets and alternately arranged on said shaft with regard to said pockets,each of said pockets having two `b'earin faces'located near and at the samev side o saidpivot, but radially inside and outside'the pivot respectively, so as to effect contact alternately with said contacts on the adjacent side of the hammer, and liniit the oscillation of said hammers in both directions fand thereby prevent overlapping' and dialling of-'adj'acentghammera testimony 'whereof I havev adined my s :l meow MlPL'AIsfrED. 

